Title: Structural evolution of Lower Carboniferous faulting and its links to fluid flow and mineralization
Researchers: Dr Koen Torremans, Prof. John Walsh
The world-class Irish Zn-Pb-(Ag) deposits comprise one of the major metallogenic provinces in the world, with over 25 deposits and prospects containing 20+ Mt of Zn+Pb metal. The majority of the Zn-Pb ore in the Irish Lower Carboniferous occurs replacing reef or reef-equivalent limestones and dolomite breccias in the hanging wall of major normal faults. These faults developed during Tournaisian and early Visean extensional tectonism and provided the necessary pathways for upward transport of metal-bearing fluids towards hanging wall traps where they are precipitated as Zn-Pb sulphides. These fault systems have been shown to strongly associate with the occurrence of individual orebody segments in the Lower Carboniferous Basin. However, despite the societal and economic importance of Irish Zn-Pb mineralization, the links between the spatial organisation of orebodies and the fault geometries are still very poorly understood, as is the evolution and timing of fault growth. Understanding the first-order structural control on these ore deposits is of great economic importance for exploitation of existing deposits and critical for predicting new deposits, given the importance of a well-connected plumbing system for metal-bearing fluids to reach their basinal traps from basement source.
The aims of this project are to define the geometry and nature of Lower Carboniferous faulting and its impact on fluid flow and Zn-Pb-Ag mineralisation. Using outcrop data, regional and mine geological, structural, drillcore and geophysical constraints, this study aims at understanding the precise nature of structurally controlled fluid flow, along laterally or vertically faults or adjacent to faults into the host rocks. A better understanding of these fundamental issues can significantly inform mineral exploration activities and reduce investment risks in the Irish Zn-Pb deposits, and will also provide useful generic insights for the analysis and exploration of other fault-controlled mineral deposits in Europe and world-wide. This project works closely with researchers in iCRAG’s 3D modelling platform and results are also integrated with many concurrent iCRAG geochemistry projects on Zn-Pb deposits.